ABSTRACT
Aim: For a simpler, more rapid and more accurate method of characterizing new isolates of Newcastle disease virus (NDV), agglutination of mammalian erythrocytes (HA) plus heat stability test and agglutination of mammalian erythrocytes plus erythrocytes elution time (EET) were compared with use of Intra-cerebral pathogenicity index (ICPI) to characterize the isolates. Materials and Methods: NDV isolates characterized by their ICPI were re-characterized by HA of mammalian erythrocytes plus heat stability test and by HA of mammalian erythrocytes plus EET. Rate of agreement of each of the two combinations with ICPI was calculated. Results: HA of mammalian erythrocytes plus heat stability agreed with ICPI in characterizing 10 of the 12 NDV isolates (83.3%) while use of HA of mammalian erythrocytes plus EET agreed with ICPI in all the 12 isolates (100%). Conclusion: It was concluded that use of combination of agglutination of mammalian erythrocytes and EET to characterize NDV isolates has better agreement with use of ICPI to characterize the virus than use of combination of agglutination of mammalian erythrocytes and heat stability test.